New swine, drug-resistant flu strains arise

Tuesday , January 10, 2012 - 2:42 PM

Erin Allday

The flu season hasn't kicked in yet, but infectious disease experts are on the alert for new strains of the virus, including another swine flu that's popped up in parts of the United States and a drug-resistant flu circulating in the Southern Hemisphere.

Since the 2009 swine flu pandemic, public health and infectious disease experts have upped their surveillance of new flu strains, and they're paying close attention to what's happening worldwide in hopes of being better prepared for the type of flu season that will hit here.

"It's better that we know what's happening earlier rather than be surprised like we were with the 2009 pandemic, which came out of the blue," said Dr. Charles Chiu, head of the viral diagnostics laboratory at University of California, San Francisco.

"We haven't seen the emergence of, say, a new pandemic strain of influenza," Chiu said. "But we've been getting these worrisome trickles of reports," which "are all reminders that influenza still poses a big threat."

Most people who get the flu suffer from fever, joint and muscle pain, coughing and fatigue before recovering without medical attention. But the flu can be deadly in older people, babies and people with weak immune systems.

New strains of flu could infect larger groups of people if humans have no natural resistance. A new, more virulent strain could be devastating -- more people could be infected and with a deadlier disease.

The focus in recent years has been on the avian flu, which has shown up primarily in Asia. Avian flu is virulent -- more than half of the people who have become infected have died -- but people can only get it from direct contact with an infected bird, and it doesn't spread from person to person. The concern is that it will mutate and become easily transmissible.

While avian flu remains a hypothetical fear, other new, if less worrisome, strains of influenza are drawing researchers' attention.

"We're not in another epidemic, but these reports give us a little warning of the (influenza) virus' capacity to mutate," said Dr. Larry Drew, head of the UCSF virology lab.

U.S. public health officials have recorded 12 cases of a new type of swine flu -- this one a form of the subtype H3N2, instead of the H1N1 subtype that made up the 2009 pandemic. Federal authorities are already preparing a vaccine to prevent the new virus' spread.

After the 2009 pandemic, influenza surveillance increased dramatically in the United States. Hundreds of labs all over the country can detect new strains that previously would have only been discovered by the Centers for Disease Control and Prevention or a handful of large state labs.

"The 2009 pandemic sort of woke everyone up," Chiu said. "... It's pretty clear that we will see another global pandemic. Whether that will be this year or next year or 10 or 20 years from now doesn't matter. It's going to happen."

To find a location for a flu shot, go to www.flu.gov.

(Email Erin Allday at eallday@sfchronicle.com. For more stories visit scrippsnews.com)